河岸带农田不同恢复年限对土壤碳氮磷生态化学计量特征的影响——以温榆河为例

弃耕地撂荒是土壤与植被向自然方向进行的次生演替,研究河岸带土壤撂荒后碳氮磷生态化学计量特征,是恢复和重建由农田干扰导致的退化河岸带生态系统的重要科学基础之一。以河岸带农地为对照,不同撂荒年限(撂荒2年、撂荒8年、撂荒10年)的土壤为研究对象,探索不同撂荒年限对土壤碳、氮、磷含量及相互关系的影响。结果表明:(1)土壤有机碳、氮的含量均呈现撂荒10年撂荒8年农田撂荒2年;土壤中磷含量呈现撂荒10年撂荒8年撂荒2年农田;农田和各撂荒年限的土壤碳、氮、磷含量,均随着土层深度的增加而呈降低的规律,但土壤碳和氮差异的显著性比磷明显。(2)河岸带土壤中C/N、C/P的均值均呈现:撂荒10年农田撂荒8年撂荒2年趋势。N/P的均值呈现:撂荒10年(0.78)农田(0.77)撂荒8年(0.77)撂荒2年(0.67),表明N是本研究区河岸带植被恢复的限制性营养元素。(3)河岸带农田和不同撂荒年限土壤碳、氮含量均存在极显著的耦合线性关系,而碳与磷、氮与磷之间的线性拟合程度相对较低。(4)在农田撂荒演替的初期阶段(2年),土壤的容重没有显著的变化,而随着撂荒时间的增加(8年和10年),土壤容重均有显著的降低,土壤结构得到改善。

Effects of different recovery years on the ecological stoichiometry characteristics of soil carbon, nitrogen and phosphorus in riparian farmland: a case study of Wenyu River

Abandoned farmland is the secondary succession of soil and vegetation toward the natural direction. Studying the eco-stoichiometric characteristics of carbon, nitrogen and phosphorus in riparian soil of the abandoned farmland is one of the important scientific bases for restoring and rebuilding the degraded riparian ecosystem caused by farmland disturbance. Taking the riparian farmland as the control, this paper studies the impacts of different abandonment years (2 years, 8 years, and 10 years) on soil carbon, nitrogen, phosphorus contents and their interrelationships in the riparian zone. The results showed that (1) the soil organic carbon and nitrogen content presented abandonment of 10 years > abandonment of 8 years > abandonment of farmland > abandonment of 2 years. The soil phosphorus content was in order of abandonment of 10 years > abandonment of 8 years > abandonment of 2 years > farmland. The soil carbon, nitrogen and phosphorus content of farmland and abandonment years decreased with the increase of soil depth. However, the difference of soil carbon and nitrogen was more significant than that of phosphorus. (2) The average values of C/N and C/P in riparian soils showed a trend of abandoning for 10 years, farmland, 8 years and 2 years. The mean values of N/P were as follows: abandonment for 10 years (0.78) > farmland (0.77) > abandonment for 8 years (0.77) > abandonment for 2 years (0.67), which indicated that N was the limited nutrient element for vegetation restoration in riparian zone of the study area. (3) There was a significant coupling linear relationship between C and N contents in riparian farmland and soils with different abandonment years, but the linear fitting degree between C and P, N and P was relatively low. (4) At the initial stage of abandonment succession (2 years), the soil bulk density did not change significantly, but with the increase of abandonment time (8 years and 10 years), the soil bulk density decreased significantly and soil structure improved.